When in the Reassembly State, the Receiver reads a 2-byte SNDU Length
field from the TS Packet payload. If the value is less than or equal to
4, or equal to 0xFFFF, the Receiver discards the Current SNDU and

It should say:

When in the Reassembly State, the Receiver reads the first two bytes
from the TS Packet payload. This value forms the first 2 bytes of the
SNDU base header, which is a combination of the D-bit and the
SNDU-Length. If the combined value is less than or equal to 4, or equal
to 0xFFFF (i.e. D=1 and SNDU Length = 32768), the Receiver MUST discard
the Current SNDU and